Apparatus for making cast bodies with inserted coils



A. T. RICHARDSON Filed oct. 21, 1944 Patented Sept. 6, 1949 APPARATUS FOR MAKING CAST BODIES WITH INSERTED COILS Arthur T. Richardson and Warren A. Smith, Geneva, Ill., assignors to Smith & Richardson Manufacturing Company, Geneva, Ill., a corporation of Illinois Application October 21, 1944, Serial No. 559,868

2 Claims.

The invention relates to the formation of female screw-threads in metal castings.

When screw-threads are formed in aluminum or other soft metals the screw-thread of a tapped hole has a tendency to sieze or become embedded in any irregularity or rough spots present on the male screw inserted in the hole, and in many instances in tightening or unscrewing the male screw the female threads are torn out of the parent metal or irreparably damaged. To overcome these objections to tapped holes it has been proposed to cast a helical coil of wire of the desired physical strength or hardness in elements formed of soft metal to form female screw-threads in said elements.

One object of the invention is to provide a composite element with a helical coil of wire of the desired physical properties and having a crosssectional shape conforming to the thread of a mating male screw embedded in the cast metal and securely enclosed therein against displacement by stresses applied to the female thread by the mating screw.

Another object of the invention is to provide improved means and a method for use in eX- pediting the fabrication of elements composed of wire coils and cast metals by which the composite elements can be accurately produced and at a low cost.

Another object of the invention is to provide improved means and a method for casting coil inserts in elements provided with ribs or lugs.

Other objects of the invention will appear from the detailed description.

The invention consists in the several novel features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawings:

Fig. 1 is a side elevation of a mandrel used in casting the wire forming the screw-thread in elements formed of cast metal,

Fig. 2 is an elevation of the mandrel with a coil of wire thereon for use in casting the coil in the element, and positioned in a pattern and sand mold.

Fig. 3 is a plan of the coil of wire used for form'- ing the female screw-thread in the casting.

Fig. 4 is a section of the mandrel with the coil of wire for forming the female thread in the mold after the pattern has been removed and before the metal has been poured into the mold and around the coil.

Fig. 5 is a section illustrating a completed element with the coil of wire forming the female screw-thread and embedded in the cast metal.

Fig. 6 is a section of an assembled face-plate mandrel and coil of wire around the mandrel and held in a pattern for embedding the coil of wire in a cast rib or lug.

Fig. 7 is a Section of a fabricated element including a coil of wire forming a screw-threaded opening in a cast lug or rib, and a face-plate.

Fig. 8 is a side elevation of the parts shown in Fig. '7.

In carrying out the invention a female screwthread is formed in a casting I2 by a coil of wire, the inner periphery of which is V-shaped in crosssection to conform to the thread of the male screw to be used with the female thread. Preferably this wire is rectangular in cross section with V-shaped outer sides which are embedded in cast metal. The wire coil is formed of metal having the desired physical properties for strength and Wear, and preformed into a helical coil I0. Each end of the coil Iii is extended radially outwardly and reverted to form an outer coil II of several convolutions which surrounds the coil I to provide adeouate portions for a rigid anchoring effect of the wire in the casting I2. Preferably the wire is twisted about between the inner coil I Il and the outer coil I I and the outer coil has one of its four sides wound around the inner coil, as illustrated in Figs. 2, 3 and 5.

In fabricating elements with the wire-coil embedded in the cast metal I2 of the element, the coil l!) is supported on the stem I 4 of the mandrel I3. This stem is provided with a screw-thread Illa which conforms to the inner periphery of the wire-coil In so that the coil can be screwed onto the stem with a fit which will prevent molten metal from flowing in the hole bounded by the inner periphery of coil Ill. The mandrel is also used to support the wire-coil in the mold. The upper end of the mandrel has a polygonal head I'I whereby it may be turned for screwing the coil onto and off the stem I4. The mandrel is adapted to be supported with the coil thereon, by the sand rammed in one of the sections of the mold. A collar I5 is screw-threaded to the stem I4 of the mandrel and seated against a shoulder I6 on said stem. Collar I5 has a flange 22 which is adapted to rest on the exposed face of a pattern 20 in a section '2| of the mold to support the mandrel and the wire-coil thereon, while sand is rammed in the other section 24 of the mold and around the upper portion of the mandrel so that the coil will be supported in mold section 24 after the pattern 20 has been removed from the other section 2| of the mold.

In practice it has been found important to anchor the end portions of the wire-coil in the cast metal so that when a male screw is manipulated in the wire-coil embedded in the cast metal, and the male screw is started into or being removed from the rst or second convolutions of the coil. the concentrated stresses on said convolutions will not displace them from the cast metal. For this purpose one end i the cpil terminates a sucient distance below the face of the casting engaged by the male: screw sti-that some of the cast metal is caused to flow between the end convolution of thev coil and said. face. This spacing of the end convolution of the coil from the working face of theelementfandnowihg of metal between the end face of the coil and' said working face and formed by the annular rib or extension |18, causes the cast metal to reinforce the end-convolution of the wire coill. against displacement from the. cast metal. Rib i8 has a downwardly tapered periphery which, extends intol the, mold cavity Z so that the collar can be withdrawn from the castmetal. By this means the convolutions at the end of coil i!! are securely anchored in and reinforced by the cast metal to prevent them from being pulled out or stripped from the cast metal by the male screw.

In making the,- composi'te, element,A the, coil iii is screwed onto the stem i4 ofthe mandrel i3 with .its upper. end against the annular rib. i3 on. the collar I'5. Sand is rammed inthe. mold.- section 2.! around. the pattern ZU which is provided with a` cavity ,2.3. for receiving the wirewoil Hl.. The stem of the mandrel. and the wire-coil are. inserted into the recess 23 in. the pattern as illustrated in Fig.. 2. The. ange 22 oi collar i5 is placed on. the upper face .of the pattern. 2d so that, the. mandrel and. wrefcoil. will be sup-ported by the pattern.. Sand is. then rammed into the mold section 24. and around the upper portion of the mandrel and around the collar.. The mold sections are. then parted. and the pattern 2Q removed. from section 2L, as illustrated in. Fig. 4, while. the mandrel and wirefcoil. are, supported from the rammed sand in. moldrsection 2e. Metal is, then.. poured. into, the cavity 25 between the; mold sectionsr so it will flow around. the. wirecoil and the annular rib i8. ot the collar i5, and between the upper end convolution .of coil i B and the lflange 22 of collar i5.. The mold sections are then parted and the mandrel. withV collar i5 thereon unscrewed from the wire. coil so .that the composite element illustrated. in FigA 5 will be, formed. This.. exemplifies a composite article which. comprises a wirewoil of suitable. metal embedded ina body of cast metal and in. which vthe end oi the .coil is spaced. from. and securely anchored in` the cast. metal to prevent the coil from being stripped. from .or .pulled out. of .the casting by screw pressure from an .inserted screw. The. vcoil .extensions` l lsupplement this. anchoring effect of thecoil in the casting.

Figs. 6, '1 .and 8 .exempliiy a modcation o the invention for producing. threadedcopenings in the ribs or lugs of a cast .body .or element. in connection with aV face plate. extending around .the lugs or ribs. The. .body I2??L is provided with a .rib or lug l2". A ysheet metal plate 23 has sides and. an end. fitting around the sides. .and end. of the rib .or lug .iZb to. iorm a` facing or reinforcement `around .the hole through the rib.. A coil of wire lila, diamond shaped in `.cross section, has integral oonvolutions .l la surrounding the .end portions. of the coil lila, and is embedded in the/cast metal lug Aor rib 12b on the .body We. In` fabricating this form of the invention, the wire-coil is supported by a bolt 30 which functions as a mandrel and comprises a stem 32 provided with a screwthread conforming to the inner periphery of coil lila, a head on one end of the stem 32 and a nut 33 threaded to the other end of said stem. The stem oithis mandrel or bolt isi adapted to extend through the opening tobe formed in the rib i2b and through openings 34 in the sides of plate 28. Nut 33 is provided with a cylindrical inward extension 35i' which ts in and extends through the opening 311 in one side of plate 28. A cylindrical portion 2G is provided on the bolt 36 adjacent head 3'I and extends through and ts in the opening. 324 in tl'ie.A other side of face plate 28. These, cylindrical extensions or portions extend inwardly to lthe outer ends of the wire-coil which are spaced' inwardly from the sides oi the face plate.. respectively, to cause some of the molten metal to ow between the outermost convolutions of the coil and the inner faces of the sides of the face plate to provide cast metal reinforcement for said convclutions. The assembled plate 28, wirecoil I'Eifi and mandrel-bolt 3 2` are placed in a pattern 4i!" which is shaped to form the body i2n with a rib or lug B2b thereon, and provided with an open ended recess 4i for receiving' the wire coil ma., as illustrated in Fig'. 6.. Sand is rammed into, la two-part. mold around the pattern '33 and the head' and nutv .on the bolt 3S and around the face plate. The. incid is then parted and the pattern. 4i! is withdrawn from one section of the mold 'while the mandrel-bolt Sil, wire-coil tripla and face plate. 28 are retained' in the rammed sand of the other section of the mold.. The rammed mold sections are then reassembled and molten metal is poured into. the cavity left by the pattern. The metal will flow to form the body or element with the rib or lug' 82h thereon, around the .wirefcoiL fill the space between the ends of the coil and the face plate, and some of the metal will ow between the end-convolutions of the wire-coil and the sides of the face-plate 2'8, When the metal has set, the mold will be, parted and' nut 33 unscrewed from the stem 32 of'bolt 3U... The bolt. can then be. unscrewed from the wireecoil embeddedv in the cast metal. The face plate, coil. and. the cast body will' then be joined together, as illustrated in Figs. 7 and 8. The portions .oi the cast metal between the end convolutions of thev wire-coil and the sides of plate 28 will reinforce said convolutions against displacement and' the ends of the coil will be securely anchored in the cast metal.

The invention exemplies a composite element .comprisingA a cast metal body with a thread-forming coil of suitable metal securely anchored in the cast metal so that the ends of thev coil. cannot be stripped from the cast metal and inwhich the coil. is solidly anchored in the cast metal against' displacement by screw pressure concentrated. at the ends yof the coil. The invention also exemplifies simple and efficient means or use. in .fabricating elements with wire-coil inserts.

The invention is not to be understood as. restricted to the details set forth since these may be modified within the scope of the appended claims without departing from the spirit and scopey of the invention.

Having thus described the inventiom what we claim as new and desire to secure by Letters Patent is:

1. A pattern and flask assembly for a mold for casting screw-thread-forming wire, coils in cast metal bodies., xcomprising: Va mould including upper and lower asksections for sand, ya pattern in the lower flask section provided with a face at the parting line of the mould, and with a downwardly extending recess in said face, a mandrel provided with a screw thread extending into the recess, a wire-coil screwed on the thread of and separable from the mandrel, in, and spaced from the side of the recess in the pattern, and having #its ends terminating in said recess, an annular abutment on the mandrel engaging said face of the pattern for supporting the mandrel with the wire coil thereon in the recess, an upwardly extending stem on the mandrel around which the sand may be interttingly packed for securing the mandrel in the upper flask section when it is separated from the pattern means on the mandrel extending into the recess to meet the upper end of the coil, and of less diameter than the outer diameter of the coil, for .forming an annular pocket in the mold for casting metal between a portion of the abutment on the mandrel and the upper end of the .coil when the pattern is removed from the mold.

2. A pattern and flask assembly for a mold for casting screw-thread-forming wire coils in cast metal |bodies, comprising: a mould including upper and lower ask sections for sand, a pattern in the lower flask section provided with a face at the parting line of the mould, provided with a downwardly extending recess in said face, a inandrel provided with a screw thread extending into the recess, a Wire coil screwed on the thread of the mandrel in, and spaced from the side of, the recess in the pattern and having its upper end terminating below said face of the pattern, a collar detachably held on the mandrel engaging said face of the pattern, for supporting the mandrel with the wire coil thereon in the recess, means REFERENCES CITED The following references file of this patent:

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